One of my hens is losing quite a bit of back feathers. I checked her back and their is only folicals. It appears as if no feathers are growing back to replace them. We have no roosters. She is acting perfectly normal except for her constantly shedding feathers. I could not find any evidence of mites or lice on any chicken. There is no bolds spots, yet. It has been cold and dry. Now it is warmer and raining. Also, I have been letting them out latter due to the weather. So, she has been getting a few less hours of light this last week. What could be the matter? Is it something to be concerned about?